Synchronous shutter for x-ray inspecting apparatus



Jan. 21, 1964 E. B. HENRY, JR., ETAL 3,119,019

SYNCHRONOUS SHUTTER FOR X-RAY INSPECTING APPARATUS Filed Feb. 27, 1961 3Sheets-Sheet l 650 65 J. K/RCHNER B, MflW Attorney Jan. 21, 1964 E. B.HENRY, JR., ETAL 3,119,019

SYNCHRONOUS'SHUTTER FOR X-RAY INSPECTING APPARATUS Filed Feb. 27, 1961 3Sheets-Sheet 2 L LLB, M,

//v VEN TORS EDWIN a. HENRY Jn, GEORGE .1. K/RCHNER A/lorney Jan. 21,1964 E. B. HENRY, JR., ETAL 3,119,019

SYNCHRONOUS SHUTTER FOR X-RAY INSPECTING APPARATUS Filed Feb. 27, 1961 3Sheets-Sheet 5 //V VEN TORS DWI/V B. HEN/P) Jr.

Aflornay United States Patent Ofice 3,119,019 SYNCHRUNOUE SHUTTER FQRX-RAY INSPECTING APPARATUS Edwin B. Henry, .Ira, Mount Lebanon Township,Alle= gheny County, and George J. Kirchner, Whitehall Bore,

Pa, assignors to United States Steel Corporation, a

corporation of New Jersey Filed Feb. 27, 1961, Ser. No. 91,873 Claims.(Cl. 250-105) This invention relates to a shutter for a radiationapparatus.

Although our invention is not thus limited, our shutter is particularlyuseful as applied to an X-ray fluoroscopy pipe-inspecting apparatus. Itis known to employ such apparatus for inspecting welds in large diameterelectrically welded steel pipe. The apparatus includes a relatively longstationary horizontal boom and a conventional X-ray head mounted on theend of the boom. A cooperating movable carriage supports the pipe andcarries it over the boom with the X-ray head focused on the weld. Aninspector watches a fluoroscope situated outside the pipe and observesany impenfections which the X-rays reveal in the weld. For a morecomplete explanation of the construction and operation of this type ofapparatus, reference may be made to a printed publication Pipe LineIndustry, August 1959 issue.

One problem encountered in using such apparatus is that the end portionsof a weld are not readily inspected. As the end of a continuously movingpipe passes the X-ray head, it exposes a portion of the fluoroscopedirectly to the X-ray head. If the head is energized at this time,intense radiation produces a brilliant glow on the fluoroscope so thatthe inspector cannot see any imperfections. Consequently the usualpractice is to energize the X-ray head only after the pipe fully coversit and to cut off the X-rays just before the last quarter inch of pipereaches it. Consequently the end portions of the weld can be fullyinspected only if the carriage is stopped. conventionally the endportions are handwelded and more likely to contain imperfections thanthe remainder, which is machine-welded. Hence the inspection isineffective for the most critical part of the Weld. Nevertheless it isapparent our invention may be used elsewhere for overcoming analogousproblems.

An object of our invention is to provide a shutter which automaticallymoves in synchronism with relative movement of an article to cover aportion of a ray-directing means left exposed as the ends of an articlepass thereover.

A further object is to provide, in combination with an X-ray pipeinspecting apparatus, an automatically operated shutter which enablesthe apparatus to be used for inspecting substantially the entire weld,including the end portions, while the pipe continues in motion.

A more specific object is to provide, in combination with an X-ray pipeinspecting apparatus, a shutter adapted to cover the X-ray head and adrive for automatically moving the shutter in synchrouism with the pipe,whereby the shutter prevents direct exposure of the fluoroscope to thehead as either end of a pipe passes.

In accomplishing these and other objects of the invention, we haveprovided improved details of structure, a preferred form of which isshown in the accompanying drawings, in which:

FIGURE -1 is an end elevational view, with parts broken away, of anX-ray pipe-inspecting apparatus equipped with our shutter and a pipepositioned thereover;

FIGURE 2 is an end elevational view partly in section showing the X-rayhead and shutter on a larger scale;

3 ,lls,tli9 Patented Jan. 21, 1964 FIGURE 3 is a side elevational viewon line III-III of FIGURE 2; and

FIGURE 4 is a schematic wiring diagram.

FIGURES 1, 2 and 3 show an X-ray pipe-inspecting apparatus whichincludes a tubular horizontal boom 10 fixed at one end to a suitablesupport, not shown, a shelf 12 fixed to the free end of the boom forangular adjust ment about the boom axis, a table 13 mounted on the shelffor sliding adjustment transversely of the boom axis, and an adjustingscrew 14- journaled to the shelf and threadedly engaged with the table.A conventional X- ray head 15 is fixed to table 13, as with clamps 16,and has an opening 17 through which it emits rays. An electric cable 18extends through boom 10 to conduct current to electrically operatedmechanism mounted on the boom, such as the X-ray head. A cooperatingcarriage 26) carries a pipe P over the boom and X-ray head. The carriageruns along rails 21 and is propelled through a motor-driven pinion 22which meshes with a gear rack 23 intermediate the rails. The carriageincludes a cradle 24 on which pipe P actually rests. The pipe has alongitudinal Weld W, and of course is positioned for X-rays emittedthrough opening 17 to be directed through this weld. An inspectorobserves the weld through a conventional fluoroscope unit 25 outside thepipe opposite the X-ray head. The structure thus far described is knownand not of our invention; hence no more detailed description is deemednecessary.

In accordance with our invention, a bracket 28 is fixed to the edge oftable 13 and extends under the X-ray head 15 (FIGURE 3). A shutter 29'is pivoted to the bracket on an axis which intersects the transversecenter line of opening 17. The shutter includes a hub 30 journaled to astub shaft 31 fixed to the lower edge of the bracket, radial arms 32fixed to the hub, an arcuate frame 33 fixed to the ends of these arms,and spaced arcuate lead shields 34 and 34a fixed to the frame. The spacebetween the two shields forms a window 3-5. Shutter 29 has a firstposition in which its shield '34- covers opening 17 in the X-ray head15, a second position in which its window 35 exposes this opening, and athird position in which its other shield 34a covers the opening. Theshutter is driven from a Selsyn motor 36 mounted on bracket 28. Motor 36is connected to the shutter via a speed reducer 37, a spur gear 38, anda gear segment 39 fixed to hub 30 and meshing with the spur gear.

We energize the Selsyn motor 36 from a transmitter 40 mounted oncarriage 20 beneath cradle 24 (FIGURE 1). We drive this transmitter fromthe shaft on which the drive pinion 22 is mounted through a chain andsprocket connection 41 and an electric brake and clutch device 42.Normally the brake of the latter device is set and the clutchdisengaged, whereby the transmitter 49 and motor 36 do not operate andshutter 29 remains stationary. When the brake is released and the clutchengaged, as hereinafter explained, the transmitter moves proportionallyto the carriage, both as to magnitude and direction. Motor 36 undergoessimilar movement, whereby it drives the shutter at the same speed and inthe same direction as pipe P is traveling.

We employ photoelectric means for controlling our brake and clutchdevice 42 and thus controlling operation of our Selsyn transmitter 49and movement of our shutter. As shown in FIGURE 3, we mount first andsecond light sources 43 and 43a on the X-ray head 15 approximately inline with the respective side edges of opening 17. The mounting meansincludes a circular clamp 4 fixed to the X-ray head, and an elongatedbracket 45 fixed to the upper edge of the clamp. Bracket 45 has slots 46and 46a in which the respective light sources 43 and 43:: are mountedfor horizontal adjustment to regulate the exact points at which theshutter operates. The light sources direct light beams at first andsecond photocells 47 and 47a respectively located outside the pipe(shown only in the schematic diagram of FIG- URE 4).

FIGURE 4 shows schematically our preferred control circuit. This circuitincludes lines 5% and 51 connected to a suitable power source, brake andclutch coils 52 and 53 embodied in the brake and clutch device 42, andrelays A, B and C. Relay A has back and front contacts A and A and itscoil is connected to the first photocell 47, whereby the relay picks upwhen the photocell is exposed to light from the light source 43 butotherwise drops out. Relay B has back and front contacts B and B and itscoil is connected in a similar relation to the second photocell 47a.Relay C has back contacts C connected in series with the brake coil 52across lines 53 and 51, and front contacts C connected in series withthe clutch coil 53 across these lines. Thus the brake coil 52 remainsenergized and the Selsyn transmitter 40 does not operate as long asrelay C is not energized and its back contacts C remain closed. Whenrelay C picks up and its front contacts C close, the clutch coil 53 isenergized and the Selsyn transmitter operates.

The coil of relay C is connected in series with the back contacts A andthe front contacts B across lines 59 and 51, and also in series withfront contacts A and back contacts B whereby relay C can be energizedvia either set of contacts. As long as pipe P breaks neither light beam,both relays A and B are energized, their back contacts A and B are open,and relay C is deenergized. When the leading end of pipe P, moving fromright to left as viewed in FIGURE 3, breaks the beam to photocell 47,relay A drops out, its back contacts A close, and relay C picks up viacontacts A and B When the leading end breaks the beam to photocell 47a,relay B drops out, its front contacts B open and relay C drops out. Alsothe back contacts B close to condition the other current path to thecoil of relay C. When the trailing end of the pipe exposes photocell 47,relay A again picks up, its front contacts A close, and relay C picks upvia contacts A and 13;. When the trailing end exposes photocell 47a,relay B again picks up, its back contacts B open and relay C drops out.Relays A and B act in the reverse sequence when the pipe travels in theopposite direction on its return.

Before carriage moves a pipe P toward the left over the X-ray head 15,the X-ray head and the light sources 43 and 43a are energized. Shutter29 occupies its first position in which its shield 34 fully coversopening 17. When the leading end of the pipe commences to cover opening17, it also breaks the light beam to photocell 47, whereupon the shutterautomatically moves counterclockwise in synchronism with the leading endof the pipe and progressively exposes the end portion of weld W toX-rays emitted through opening 17. As the shutter reaches its secondposiiton in which its window 35 fully exposes opening 17, the leadingend of the pipe breaks the light beam to photocell 47a, whereupon theshutter stops. As the trailing end of the pipe subsequently exposesphotocell 47, the shutter automatically moves counterclockwise insynchronism with the trailing end, and its shield 34a progressivelycovers opening 17 as the trailing end exposes it. As the shutter reachesits third position in which its shield 34a fully covers opening 17, thetrailing end exposes photocell 47a, whereupon the shutter stops. Thereverse action takes place as the pipe moves back from left to right.Thus the inspector is able to observe both end portions of the weldwhile the shields 34- and 34a eliminate glare as the ends of the pipepass opening 17. Normally we adjust the positions of the light sources43 and 43a in bracket 45 so that the shields have a lap of about /2 inchover the pipe ends, since the ends are cropped to this extent.Nevertheless we can adjust the parts to avoid any lap and inspect theentire weld.

From the foregoing description it is seen that our invention affords asimple shutter, and an operating mechanism which automatically moves theshutter in synchronism with an article as the ends of the article pass aray-directing means. As applied to a pipe inspecting apparatus, ourinvention enables a weld to be inspected throughout its length while thepipe continues in motion. Our shutter is readily installed on existingequipment, and it enables the equipment to perform a more rigidinspection and to include the most critical portions of a weld.

While we have shown and described only a single embodiment of theinvention, it is apparent that modifications may arise. Therefore, we donot wish to be limited to the disclosure set forth but only by the scopeof the appended claims.

We claim:

1. in an apparatus which includes means for directing rays on an articletraveling relatively thereto, the combination therewith of a shuttermounted for movement to different positions in which it covers orexposes said raydirecting means, and a drive mechanism operativelyconnected with said shutter for moving the shutter in synchronism withthe relative movement of the article at the same speed and in the samedirection for covering the portion of said ray-directing means leftexposed as at least one end of the article passes thereover.

2. In an apparatus which includes means for directing rays on an articletraveling relatively thereto, the combination therewith of a movableshutter, which in the absence of an article normally covers saidray-directing means and in the presence of an article normally exposessaid ray-directing means, and a drive mechanism operatively connectedwith said shutter for moving the shutter in synchronism with therelative movement of the article at the same speed and in the samedirection for covering the portion of said ray-directing means leftexposed as the ends of the article pass thereover.

3. In an X-ray pipe-inspecting apparatus which includes a support, anX-ray head mounted on said support, and means for relatively moving apipe over said head, the combination with said head of a shutter movablymounted on said support, and a drive mechanism operatively connectedwith said shutter for moving the shutter in synchronism with therelative movement of the pipe for partially covering said head as atleast one end of the pipe passes thereover.

4. In an X-ray pipeinspecting apparatus which includes a support, anX-ray head mounted on said support, and means for relatively moving apipe over said head, the combination with said head of a shutter mountedon said support for movement to different positions in which it coversor exposes said head, and a drive mechanism operatively connected withsaid shutter for moving the shutter in synchronism with the relativemovement of the pipe for covering the portion of said head left exposedas at least one end of the pipe passes thereover.

5. In an X-ray pipe-inspecting apparatus which includes a support, anX-ray head mounted on said support, and means for relatively moving apipe over said head, the combination with said head of a shutter movablymounted on said support, said shutter in the absence of a pipe normallycovering said head and in the presence of a pipe normally exposing saidhead, and a drive mechanism mounted on said support and operativelyconnected with said shutter for moving the shutter in synchronism withthe relative movement of the pipe for covering the portion of said headleft exposed as the ends of the pipe pass thereover.

6. In an X-ray pipe-inspecting apparatus which includes a support, anX-ray head mounted on said support, and means for relatively moving apipe over said head, the combination with said head of a shutter movablymounted on said support, said shutter in the absence of a pipe normallycovering said head and in the presence of a pipe normally exposing saidhead, a drive mechanism mounted on said support and operativelyconnected with said shutter for moving the shutter in synchronism withthe relative movement of the pipe to expose and cover said head, andphotoelectric means for actuating said drive mechanism as the ends of arelatively moving pipe reach and later clear said head, whereby saidshutter covers the portion of said head left exposed by the pipe as itsends pass thereover.

7. In an X-ray pipe-inspecting apparatus which includes a support, anX-ray head mounted on said support, and means for relatively moving apipe over said head, the combination with said head of a shutter movablymounted on said support and having a pair of spaced apart shields and awindow between said shields, said shutter in the absence of a pipenormally occupying a position in which one of said shields covers saidhead and in the presence of a pipe a position in which said windowexposes said head, a drive mechanism mounted on said support andoperatively connected with said shutter for moving the shutter insynchronism with the relative movement of the pipe to expose and coversaid head, and means for actuating said drive mechanism as the ends of arelatively moving pipe reach and later clear said head, whereby one ofsaid shields moves in advance of the leading end of the pipe and theother shield moves behind the trailing end to cover the portion of saidhead left exposed by the pipe as its ends pass thereover.

8. In an X-ray pipe-inspecting apparatus which includes a support, anX-ray head mounted on said support, and a cooperating carriage formoving a pipe over said head, the combination with said head of ashutter movably mounted on said support and having a pair of spacedapart shields and a window between said shields, said shutter in theabsence of a pipe normally occupying a position in which one of saidshields covers said head and in the presence of a pipe a position inwhich said window exposes said head, a motor mounted on said support fordriving said shutter, a transmitter mounted on said carriage andoperatively connected thereto for energizing said motor and thus movingsaid shutter in synchronism with the pipe to expose and cover said head,and means for actuating said transmitter as the ends of a pipe reach andlater clear said head, whereby one of said shields moves in advance ofthe leading end of the pipe and the other shield moves behind thetrailing end to cover the portion of said head left exposed by the pipeas its ends pass thereover.

9. In an X-ray pipe-inspecting apparatus which includes a support, anX-ray head mounted on said support, and a cooperating carriage formoving a pipe over said head, the combination with said head of ashutter pivotally mounted on said support and having a pair of spacedapart shields and a window between said shields, said shutter in theabsence of a pipe normally occupying a position in which one of saidshields covers said head and in the presence of a pipe a position inwhich said window exposes said head, a motor mounted on said support andconnected to said shutter for swinging the shutter to its differentpositions, a transmitter mounted on said carriage and operativelyconnected thereto for energizing said motor and thus swinging saidshutter in synchronsim with movement of the pipe to expose and coversaid head, and photoelectric means for actuating said transmitter as theends of a pipe reach and later clear said head, whereby one of saidshields moves in advance of the leading end of the pipe and the othershield moves behind the trailing end to cover the portion of said headleft exposed by the pipe as its ends pass thereover.

10. A combination as defined in claim 9 in which said photoelectricmeans include a pair of spaced apart light sources carried by said headand a pair of corresponding photocells outside the pipe, whereby passingof the ends of the pipe controls said photocells.

References Cited in the file of this patent UNITED STATES PATENTS2,360,036 Boucher Oct. 10, 1944 2,370,163 Hare Feb. 27, 1945 2,788,896Coleman Apr. 16, 1957 2,856,539 Orthuber Oct. 14, 1958 2,858,450 HolbenOct. 28, 1958 2,894,140 Schneeman July 7, 1959 2,951,159 Mariner Aug.30, 1960 2,965,758 Malick Dec. 20, 1960 2,981,845 Larew et al Apr. 25,1961

1. IN AN APPARATUS WHICH INCLUDES MEANS FOR DIRECTING RAYS ON AN ARTICLETRAVELING RELATIVELY THERETO, THE COMBINATION THEREWITH OF A SHUTTERMOUNTED FOR MOVEMENT TO DIFFERENT POSITIONS IN WHICH IT COVERS OREXPOSES SAID RAYDIRECTING MEANS, AND A DRIVE MECHANISM OPERATIVELYCONNECTED WITH SAID SHUTTER FOR MOVING THE SHUTTER IN SYNCHRONISM WITHTHE RELATIVE MOVEMENT OF THE ARTICLE AT THE SAME SPEED AND IN THE SAMEDIRECTION FOR COVERING THE PORTION OF SAID RAY-DIRECTING MEANS LEFTEXPOSED AS AT LEAST ONE END OF THE ARTICLE PASSES THEREOVER.